A combined gas chromatography combustion-isotope ratio mass spectrometry method(GC-C IRMS) for stable carbon isotope analysis of amino acids is presented. Unlike hydrocarbons, amino acids require derivatization prior ...A combined gas chromatography combustion-isotope ratio mass spectrometry method(GC-C IRMS) for stable carbon isotope analysis of amino acids is presented. Unlike hydrocarbons, amino acids require derivatization prior to GC-C-IRMS analysis. Replicate carbon isotope analyses of trifluoroacetyl isopropyl ester derivatives of 17 amino acids by IRMS revealed that the derivatization process is reproducible. Due to a reproducible isotopic fractionation an empirical correction factor for each individual amino acid is derived separately for derivatives and the original δ^13C value of the underivatized amino acid is calculated.展开更多
该研究建立了一种精准测定不同样品中氨基酸含量及其氮同位素组成的方法。首先利用N-新戊酰基-O-异丙酯(NPP)对氨基酸进行衍生化,使其更适用于气相色谱分析。随后,采用气相色谱-质谱(GCMS)对大豆、土壤以及标准样品中的15种氨基酸单体...该研究建立了一种精准测定不同样品中氨基酸含量及其氮同位素组成的方法。首先利用N-新戊酰基-O-异丙酯(NPP)对氨基酸进行衍生化,使其更适用于气相色谱分析。随后,采用气相色谱-质谱(GCMS)对大豆、土壤以及标准样品中的15种氨基酸单体进行定量分析,所有目标氨基酸均获得良好的分离效果,且在1.0~16.0μmol/L浓度范围内呈线性关系(r^(2)>0.98)。此外,利用气相色谱-燃烧-同位素比值质谱(GC-C-IRMS)对上述样品中氨基酸的氮同位素组成(δ~(15)N)进行了测定。结果表明,当进样量超过20 ng N([N_(2)^(+)]m/z 28信号强度约为150 mV)时,该方法可以获得稳定可靠的δ^(15)N值,平均精度可达0.36‰。通过与元素分析-同位素比值质谱(EA-IRMS)的结果进行比较,两种方法的测定结果高度一致(r^(2)=0.9954),表明NPP衍生化过程未引入明显的氮同位素分馏。最终测得大豆和土壤样品中各氨基酸的δ~(15)N值分别分布在10.90‰~22.32‰和-1.92‰~12.82‰之间,标准偏差分别为0.23‰~0.88‰和0.08‰~0.79‰,符合样品分析的精度要求。展开更多
文摘A combined gas chromatography combustion-isotope ratio mass spectrometry method(GC-C IRMS) for stable carbon isotope analysis of amino acids is presented. Unlike hydrocarbons, amino acids require derivatization prior to GC-C-IRMS analysis. Replicate carbon isotope analyses of trifluoroacetyl isopropyl ester derivatives of 17 amino acids by IRMS revealed that the derivatization process is reproducible. Due to a reproducible isotopic fractionation an empirical correction factor for each individual amino acid is derived separately for derivatives and the original δ^13C value of the underivatized amino acid is calculated.
文摘该研究建立了一种精准测定不同样品中氨基酸含量及其氮同位素组成的方法。首先利用N-新戊酰基-O-异丙酯(NPP)对氨基酸进行衍生化,使其更适用于气相色谱分析。随后,采用气相色谱-质谱(GCMS)对大豆、土壤以及标准样品中的15种氨基酸单体进行定量分析,所有目标氨基酸均获得良好的分离效果,且在1.0~16.0μmol/L浓度范围内呈线性关系(r^(2)>0.98)。此外,利用气相色谱-燃烧-同位素比值质谱(GC-C-IRMS)对上述样品中氨基酸的氮同位素组成(δ~(15)N)进行了测定。结果表明,当进样量超过20 ng N([N_(2)^(+)]m/z 28信号强度约为150 mV)时,该方法可以获得稳定可靠的δ^(15)N值,平均精度可达0.36‰。通过与元素分析-同位素比值质谱(EA-IRMS)的结果进行比较,两种方法的测定结果高度一致(r^(2)=0.9954),表明NPP衍生化过程未引入明显的氮同位素分馏。最终测得大豆和土壤样品中各氨基酸的δ~(15)N值分别分布在10.90‰~22.32‰和-1.92‰~12.82‰之间,标准偏差分别为0.23‰~0.88‰和0.08‰~0.79‰,符合样品分析的精度要求。
